Two New Zealand inventors have produced what they claim are the world's first robotic legs to help paraplegics walk again.

The bionic legs were road-tested publicly for the first time Thursday by 23-year-old Hayden Allen who was told five years ago he would never walk again after being paralyzed from the chest down in a motorcycle accident.

Allen said the experience of being able to stand up and walk when strapped into his robotic legs was fantastic and he felt like a normal human being again.

"It will be a big benefit from a social aspect, being able to talk to someone at the same eye level," he told reporters.

Inventors Richard Little and Robert Irving, two expatriate Scottish engineers who emigrated in the early 1990s, came up with the idea seven years ago and have spent 10 million dollars (US $7.1 million) developing it.

Called Rex (robotic exoskeleton) the 38 kilogram (84 pounds) joy-stick operated legs were inspired by the movie "Aliens" in which the character Ripley (Sigourney Weaver) climbs into a robotic exoskeleton to fight an alien.

Rex is "a realistic standing and walking alternative to wheelchairs," the inventors said on their website Rexbionics.com.

"It enables the user to climb up and down stairs, sit, stand, and step backwards, sideways and forwards -- providing the opportunity for people in wheelchairs who want to walk, to do just that."

However, Rex comes with a hefty price tag of US $150,000 and at present is only available in New Zealand although the inventors said it would be sold worldwide from next year.

Rex Bionics, which now employs 25 mechatronic and software engineers, believes demand will outstrip supply for the next few years and they have already had enquiries suggesting people will pay up to US $250,000.